Once upon a time there was a browser named Firefox -- an open source project that many people happily picked up and spun off into their own versions with names like Iceweasel and Pale Moon. Now the same thing has happened with Google Chrome. Its open source incarnation, Chromium, has become the basis for a slew of spinoffs, remixes, and alternative versions.

Naturally, a variant version of a browser needs to be broadly compatible with the original to be useful, but at the same time have enough new features or enhanced functionality to be a compelling alternative. Just as a remix of a song combines something from the original with something new, Chrome spinoffs inherit Chrome's speed and rendering prowess while striking off in new directions.

When is it worth ditching Chrome for a Chromium-based remix? Some of the spinoffs are little better than novelties. Some have good ideas implemented in an iffy way. But a few point toward some genuinely new directions for both Chrome and other browsers. Here's a rundown of the ones we think are the most interesting: Chromium, SRWare Iron, Comodo Dragon, RockMelt, CoolNovo, and Chrome itself.

Chromium

The first place to start is the one closest to home. The open source core of Chrome, Chromium is what the browser is before Google adds its branding and integration features. These include things like user metrics (the sending of browsing stats back to Google), crash reporting, the built-in Flash player and PDF viewer, multimedia codecs (MP3, AAC), and the auto-updating system. Folks who lambast Google over privacy issues often recommend using Chromium, which lacks the user tracking features they dislike in Chrome.

Browsing in Chromium is virtually the same experience as using Chrome itself, in big part because many of the missing pieces are made up for in other ways. The lack of the internal Flash plug-in isn't a problem, for instance, because Chromium can make use of whatever copy of Flash is already installed in Windows.

One potential hurdle is that Chromium isn't distributed in the same manner as Chrome itself. There are automated builds of Chromium in the maze of directories for Google's Chromium site, and anywhere from four to five builds a day are created automatically from the latest source code. But because Chromium doesn't have Chrome's auto-updater, you need to upgrade Chromium manually.

Another problem is Chromium's inherent instability. If you simply pick a build, there's no guarantee it will run properly, so you may have to do some research ferreting out a reasonably stable one. Fortunately, some people have done a little of this legwork for you. For instance, the CRportable project repackages reasonably stable Chromium builds in the PortableApps format, so you can run the browser from a USB key or portable hard drive.

A "portable" version of Chromium, the open source core from which Chrome is derived. The privacy settings at the top have been disabled by the user.